An efficient algorithm for ray casting of CSG animation frames

This paper presents a new algorithm to generate ray casted CSG animation frames. We consider sequences of frames where only the objects can move, in this way, we take advantage of the high screen area coherence of this kind of animation. A new deenition of bounding box allows us to reduce the number of pixels to be computed for the frames after the rst. We associate with each box a CSG sub-tree encapsulated and two ags denoting if the box has changed in the current frame and if it will change in the next frame, respectively. We show with two examples the advantages of our technique when compared with an algorithm which entirely renders each frame of an animation. For the test sequences the intersections with CSG objects may be reduced about up to one fth, while the rendering may be computed up to four times faster.